Definition: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Input: Article: Christmas Day, the birthday of Jesus Christ, is the most important festival in prefix = st1 /Britainand some other countries. On Christmas Eve, people usually tell their children to put their stockings at the end of their beds before they go to sleep. Children believe Santa Claus, with the other name of Father Christmas, will come during the night and fill their stockings with Christmas presents.   Actually , Father Christmas is children's father. He dresses up in a red coat and waits until children fall asleep. Then he goes into children's bedrooms, and puts small presents in their stockings. When children are no longer young, they know who Father Christmas really is.   Not only children but also their parents enjoy Christmas stockings. They also have stockings. Early on the morning of Christmas Day, children wake their parents up and say"Merry Christmas". Then they help their parents open their stockings. Everybody likes presents. But it is better to give than to receive. 
 Answer: the birthday of Jesus Christ

Christmas Day is  _  .